The hero's entire childhood was spent in long hours of training under the watchful eye of his father. They lived in seclusion, with no other people around. The jungles became the territory where the young boy grew and transformed into a true warrior. His father was determined to raise his son as a samurai, whose exploits he would be proud of. The child was deprived of contact with peers and had a weak understanding of what human society was like. And all of this will have a negative impact on him when he leaves the embrace of nature and enters civilized conditions.
Upon arriving in Japan, Kuroganye Yaiba becomes actively involved in the bustling flow of modern life. However, he has a goal for which he came to the city environment. It is related to the person of Onimaru Takeshi. He is a formidable fighter, whom only an advanced master can defeat. In addition, he gains possession of the legendary demon sword. Yaiba is bewildered by his surroundings. Meeting girls is a huge surprise for him, as he never even imagined what they looked like. At the same time, he must quickly adapt to the hustle and bustle of the city, and soon incredible adventures await him.